1. Technical Field
The technical field relates to an optical gas sensor.
2. Background
A gas sensor is a device having important meaning for human life and health. Demands for gas detection are wide, for example, in the fields of home environment monitoring, industrial safety, and disease diagnosis and treatment. Moreover, due to the requirements for industrial safety and environmental regulations, the gas sensor plays an important role.
Gas sensors can be divided into different categories by the kinds of gases to be detected or by the working principles. The working principles of the gas sensors have electrochemistry, solid electrolyte, optics, oxide semiconductor etc. The first-generation gas sensor is a liquid electrochemical gas sensor. Such liquid electrochemical gas sensor has strong corrosion of the electrolyte solution, large volume and need for regular maintenance. Since the solid-state gas sensor can be miniaturized, it is in mass production to replace the liquid electrochemical gas sensor. However, the solid-state gas sensor requires a micro-heater to raise its temperature and thereby sensitivity, the sensing material thereof has specificity for the gas to be detected, and the solid-state gas sensor needs to contact the gas to be able to use. Therefore, in the use of the solid state gas sensor, attention should be paid to flashover caused by the high temperature, detection failure due to contaminated sensing material etc.
The current optical gas sensor has a complicated optical system and cannot be easily miniaturized and fabricated in batch production, so that it is not affordable in the market. Therefore, how to simplify and miniaturize the optical gas sensor to fabricate one integrated platform at a wafer level has been drawn highly attention in the industry.